Using an Ohmmeter to Measure Resistors

The multimeter is probably the most used piece of equipment on an electronics bench. Multi implies that the meter has multiple functions. Most multimeters can perform the following functions.

• Measure voltage - Voltmeter
• Measure current - Ammeter (because current is measured in amps)
• Measure resistance - Ohmmeter (because resistance is measured in ohms)

In this guide we are going to use our multimeters in ohmmeter mode, or simply "in ohms".

Example Ohmmeters

Here we will show you 3 different multimeters and how to put them in ohmmeter mode.

Fluke	Craftsman	EmCo
Set dial to Ω Connect probes to COM and Ω 0.L displayed with nothing hooked up Meter determines range automatically	Press button labeled Ω Connect probes to COM and Ω 00.0 displayed with nothing hooked up Meter determines range automatically	Set dial to green number within Ω range Connect probes to COM and Ω 1. displayed with nothing hooked up You pick range to measure in

As you can see, all 3 of these meters have different procedures for putting them in ohmmeter mode. You will have to figure out how your meter works based on these examples. The important things to note are:

• Know where to set your dial
• Figure out which plugs to connect your wires to
• Understand what the display is showing

How to Hold The Resistor

The correct way to connect a resistor to an ohmmeter is with spring loaded clips, like this.

This is correct.

Now we will show the the incorrect way to hold a resistor. Do not do this!

This is incorrect!

By using your fingers to hold the resistor to the probes you have changed the resistance that you are measuring. You will not get accurate results if you do this. If you do not have spring clips, then set the resistor down on something like a piece of paper or a plastic cutting board and press the probes into it without touching them.

Hooking Up the Meters

Once you get your meter set up correctly, you can clip on to the resistor and get an accurate reading of its value. Here are the above 3 meters measuring the same resistor.

Fluke	Craftsman	Em-Co
The meter is reading 990 ohms	The meter is reading .989k ohms (which is 989 ohms)	The meter is reading .986k ohms (which is 986 ohms)

As you can see, all 3 meters are reading a different value. You can not quite make out the bands of the resistor in the picture, but they are:

This seems reasonable. All meters are reading pretty darn close to 1k ohm. When using a meter to measure a resistor you will have to get used to values being close, but not quite exact. All meters are calibrated slightly differently and will read slightly different than each other.